1. Field of the Invention
This invention relates to a clip for retaining a grid simulating muntins, and more particularly, to retainer clips for securing a grid simulating muntins within a spacer frame between adjacent sheets of a multi-sheet unit with the connection between the clips and the ends of the grid below the sight line of the unit.
2. Discussion of the Available Technology
Clips usually referred to as retainer clips or muntin clips are used to mount grids simulating muntins within a spacer frame between adjacent sheets of a multi-sheet insulating unit, e.g. as discussed in U.S. Pat. Nos. 5,313,761 and 6,115,989, and United States Patent Publication Numbers US2004/0123557 and US2005/0028458A1. In general, but not limiting to the discussion, a two sheet insulating unit includes a pair of glass sheets secured to sides of a closed spacer frame by a moisture and gas impervious adhesive-sealant to provide a sealed compartment between the sheets. The sealed compartment is usually filled with an insulating gas. The spacer frame in one embodiment of a multi-sheet insulating unit has a U-shaped cross section, e.g. as disclosed in U.S. Pat. No. 5,655,282. One of the features of a spacer frame having a U-shaped cross section is the movement of the upright legs of the spacer frame toward and away from one another in unison with the movement of the glass sheets as the insulating gas in the sealed compartment expands and contracts due to pressure changes acting on the outer surfaces of the sheets.
The current practices of mounting the grid simulating muntins within the spacer frame, includes mounting the retainer clips on the ends of the grid, and mounting the clips on the interior surface of the spacer frame, or mounting the retainer clips on the interior surface of the spacer frame followed by mounting the ends of the grid on the retainer clips. United States Patent Application Publication Number US 2004/0123557 discloses a number of retainer clip designs. Although the present design of the retainer clips is acceptable for mounting grids simulating muntins within the spacer frame of insulating glass units, there are limitations.
More particularly, many of the retainer clips have a rigid base that bridges the two upright legs of the spacer frame maintaining the upright legs in a fixed relationship to one another. The drawback with this retainer clip design is that the retainer clip prevents portions of the upright legs and marginal edges of the sheets from bending toward one another as the atmospheric pressure acting on the outside surface of the sheets increases. Another drawback with retainer clips having a rigid base is that during the pressing of the marginal edges of the sheets toward the outer surfaces of the space frame to flow the adhesive-sealant between the sheets and the spacer frame, the upright legs between adjacent retainer clips are flexible and bend or move toward one another whereas the retainer clip does not flex preventing the upright legs at the position of the retainer clip from moving toward one another. The undesirable result is the adhesive-sealant between adjacent retainer clips having a thickness greater than the thickness of the adhesive-sealant at the position of the retainer clips. This limitation results in a “moisture sealant path” or “diffusion path” having a non-uniform thickness and can result in premature failure of the seal by allowing atmospheric air to diffuse into the sealed compartment. For a discussion of the “diffusion path”, reference can be made to column 13, lines 7-43 of U.S. Pat. No. 5,655,282 which patent is hereby incorporated by reference.
Another limitation with having the base of the retainer clip supported on and spanning the upright legs of the spacer frame is that the retainer clip is in the sight line of the insulating unit. Therefore, care has to be taken to make certain that the ends of the grid simulating muntins is flush with the base of the retainer clip to avoid any space, or minimize the space, between the ends of the grid and the base of the retainer clip. Noticeable separations between the base of the clip and the end of the grid are aesthetically unacceptable.
Still another limitation with the present retainer clip design is that the retainer clips because of their design have to be injection molded or machined which are expensive operations compared to pultrusion and extrusion.
As can now be appreciated by those skilled in the art, it would be advantages to provide retainer clips that do not have the limitation of the presently available retainer clips.